There is known WAVE (Wireless Access in Vehicular Environments) as a telecommunication standard used for an intelligent transport system as disclosed in Patent literature 1.
WAVE uses two kinds of channels of a control channel and a service channel for a vehicular wireless communication device and a roadside unit to communicate with each other. The service channel is a channel used to transmit or receive the information for executing a service (i.e., service execution information, hereinafter). The service is provided as one of a plurality of kinds of services; the service channel is provided as one of a plurality of channels having mutually different frequencies. Each of the services is correspondingly associated with one of the service channels.
The control channel is a channel used for a roadside unit to transmit the various information (i.e., service announcement information, hereinafter) for announcement in order to perform communication with a vehicular wireless communication device via a service channel. To start the communication via a service channel, a reception channel that the vehicular wireless communication device uses for reception needs to be set to any one of the service channels. The service announcement information thus includes the information (channel information, hereinafter) for identifying a service channel designated as the reception channel.